package leetcode.problems;

import java.util.ArrayDeque;
import java.util.Deque;

/**
 * Created by gmwang on 2018/3/9
 */
public class _0311LongestAbsoluteFilePath {
    /**
         * Suppose we abstract our file system by a string in the following manner:
         The string "dir\n\tsubdir1\n\tsubdir2\n\t\tfile.ext" represents:

         假设我们按照以下方式通过字符串来抽象我们的文件系统：
         该字符串"dir\n\tsubdir1\n\tsubdir2\n\t\tfile.ext"表示：
             dir
             subdir1
             subdir2
             file.ext
         The directory dir contains an empty sub-directory subdir1 and a sub-directory subdir2 containing a file file.ext.
         The string "dir\n\tsubdir1\n\t\tfile1.ext\n\t\tsubsubdir1\n\tsubdir2\n\t\tsubsubdir2\n\t\t\tfile2.ext" represents:

     该目录dir包含一个空的子目录subdir1和一个subdir2包含文件的子目录file.ext。
         该字符串"dir\n\tsubdir1\n\t\tfile1.ext\n\t\tsubsubdir1\n\tsubdir2\n\t\tsubsubdir2\n\t\t\tfile2.ext"表示：
             dir
             subdir1
             file1.ext
             subsubdir1
             subdir2
             subsubdir2
             file2.ext
         The directory dir contains two sub-directories subdir1 and subdir2. subdir1 contains a file file1.ext and an empty second-level sub-directory subsubdir1. subdir2 contains a second-level sub-directory subsubdir2 containing a file file2.ext.
         We are interested in finding the longest (number of characters) absolute path to a file within our file system. For example, in the second example above, the longest absolute path is "dir/subdir2/subsubdir2/file2.ext", and its length is 32 (not including the double quotes).
         Given a string representing the file system in the above format, return the length of the longest absolute path to file in the abstracted file system. If there is no file in the system, return 0.
            Note:
         The name of a file contains at least a . and an extension.
         The name of a directory or sub-directory will not contain a ..
         Time complexity required: O(n) where n is the size of the input string.
         Notice that a/aa/aaa/file1.txt is not the longest file path, if there is another path aaaaaaaaaaaaaaaaaaaaa/sth.png.

         该目录dir包含两个子目录subdir1和subdir2。subdir1包含一个文件file1.ext和一个空的二级子目录subsubdir1。subdir2包含一个subsubdir2包含文件的二级子目录file2.ext。
         我们感兴趣的是找到文件系统中文件的最长（字符数）绝对路径。例如，在上面的第二个例子中，最长的绝对路径是"dir/subdir2/subsubdir2/file2.ext"，其长度是32（不包括双引号）。
         给定一个以上述格式表示文件系统的字符串，将最长的绝对路径的长度返回到抽象文件系统中的文件。如果系统中没有文件，则返回0。
            注意：
         文件的名称至少包含一个.和一个扩展名。
         目录或子目录的名称将不包含.。
         所需时间复杂度：O(n)这里n是输入字符串的大小。
         a/aa/aaa/file1.txt如果还有其他路径，请注意这不是最长的文件路径aaaaaaaaaaaaaaaaaaaaa/sth.png。
     */
    public static int lengthLongestPath(String input) {
        Deque<Integer> stack = new ArrayDeque<>();
        stack.push(0); // "dummy" length
        int maxLen = 0;
        for(String s:input.split("\n")){
            int lev = s.lastIndexOf("\t")+1; // number of "\t"
            int pop = 0;
            while(lev+1<stack.size()) pop += stack.pop(); // find parent
            int len = stack.peek()+s.length()-lev+1; // remove "/t", add"/"
            if(pop < len)
                stack.push(len);
            else
                stack.push(pop);
            // check if it is file
            if(s.contains(".")) maxLen = Math.max(maxLen, len-1);
        }
        return maxLen;
    }
    public static void main(String[] args) {
        System.out.println(lengthLongestPath("dir\n\tsubdir1\n\tsubdir2\n\t\tfile.ext"));
//        System.out.println(lengthLongestPath("dir\n\tsubdir1\n\t\tfile1.ext\n\t\tsubsubdir1\n\tsubdir2\n\t\tsubsubdir2\n\t\t\tfile2.ext"));
    }
}
